/* superman.c Compute Superman's flight path -- geometry example */ /* Copyright 2003-2020 by Steven S. Skiena; all rights reserved. Permission is granted for use in non-commerical applications provided this copyright notice remains intact and unchanged. These programs appear in my books: "The Algorithm Design Manual" by Steven Skiena, second edition, Springer, London 2008. See out website www.algorist.com for additional information or https://www.amazon.com/exec/obidos/ASIN/1848000693/thealgorith01-20 "Programming Challenges: The Programming Contest Training Manual" by Steven Skiena and Miguel Revilla, Springer-Verlag, New York 2003. See our website www.programming-challenges.com for additional information, or https://www.amazon.com/exec/obidos/ASIN/0387001638/thealgorithmrepo/ */ #define MAXN 100 /* maximum number of circles */ #include #include #include #include "geometry.h" point s; /* Superman's initial position */ point t; /* target position */ int ncircles; /* number of circles */ circle c[MAXN]; /* circles data structure */ void superman(void) { line l; /* line from start to target position */ point close; /* closest point */ double d; /* distance from circle-center */ double xray = 0.0; /* length of intersection with circles */ double around = 0.0; /* length around circular arcs */ double angle; /* angle subtended by arc */ double travel; /* total travel distance */ int i; /* counter */ points_to_line(s, t, &l); for (i = 1; i <= ncircles; i++) { closest_point(c[i].c,l, close); d = distance(c[i].c, close); if ((d >= 0) && (d < c[i].r) && point_in_box(close, s, t)) { xray += 2 * sqrt(c[i].r * c[i].r - d * d); angle = acos(d/c[i].r); around += ((2 * angle) / (2 * PI)) * (2 * PI * c[i].r); printf("circle %d (%7.3lf,%7.3lf,%7.3lf) is %7.3lf away from l, xray=%7.3lf around=%7.3lf angle=%7.3lf.\n", i, c[i].c[X], c[i].c[Y], c[i].r, d, xray, around, angle); } } travel = distance(s, t) - xray + around; printf("Superman sees through %7.3lf units, and flies %7.3lf units\n", xray, travel); } int main(void) { int i; /* counter */ scanf("%lf %lf", &s[X], &s[Y]); scanf("%lf %lf", &t[X], &t[Y]); scanf("%d", &ncircles); for (i = 1; i <= ncircles; i++) { scanf("%lf %lf %lf", &c[i].c[X], &c[i].c[Y], &c[i].r); } printf("%7.3lf %7.3lf\n",s[X],s[Y]); printf("%7.3lf %7.3lf\n",t[X],t[Y]); printf("%d\n",ncircles); for (i = 1; i <= ncircles; i++) { printf("%7.3lf %7.3lf %7.3lf\n", c[i].c[X], c[i].c[Y], c[i].r); } superman(); return 0; }